// virtual int gradf(MElement *ele, double u, double v, double w,std::vector<GradType> &grads, STensor3 &invjac)=0;// on passe le jacobien que l'on veut ...
/* virtual int hessf(MElement *ele, double u, double v, double w,std::vector<HessType> &hesss);
virtual int divf(MElement *ele, double u, double v, double w,std::vector<DivType> &divs);
virtual int curlf(MElement *ele, double u, double v, double w,std::vector<CurlType> &curls);*/
virtualintgetNumKeys(MElement*ele)=0;// if one needs the number of dofs
virtualintgetKeys(MElement*ele,Dof*keys)=0;// may be faster once the number of dofs is known